1. Field of the Invention
This invention relates to an apparatus for conveying an incumbent person, more particularly to an apparatus for conveying in an incumbent state a disabled person or an invalid (herein frequently referred to simply as a "person") lying on a bed, operating table, stretcher or the like and unable to stand or walk.
2. Prior Art Statement
For conveying such an incumbent person it is generally necessary to somehow bring a conveyance means near or in contact with the person and then to cause an operating force to act on the person. Conventional methods that are extensions of techniques for transporting heavy loads have been developed for this purpose and involve, for example, using an apparatus resembling a forklift to lift the person together with his bed or using a crane-like device suspended from the ceiling for lifting the person by means of a sling constituted of belts, a net or a sheet. In addition, one particularly excellent method that has been developed involves inserting a loading plate member between the person and the supporting surface (e.g. the top of a bed) and then conveying the person on the plate. In this method, the loading plate member has belts wound thereon and the belts are paid out synchronously with the movement of the plate member, thus eliminating slippage at the plate member surfaces in contact with the person and the supporting surface. The principle involved is shown in FIGS. 5(a), (b) and (c). The loading plate member 31 is constituted of upper and lower plates 31a, 31b which are separated by spacers 32 and respectively have belts 33a and 33b wound thereon. When moving toward the incumbent person 36 (FIG. 5(a)), the belt 33a on the upper plate rotates counterclockwise while the belt 33b on the lower plate rotates clockwise. The reference numerals 34 and 35 respectively denote the main body of the apparatus and the support (e.g. bed) on which the person 36 is lying. The upper plate 31a moves beneath the person 36 (FIG. 5(b)) and then after the person has been completely loaded on the upper segment of the loading plate member 31 as shown in FIG. 5(c), the loading plate member 31 is returned to the main body 35. At this time, the lower belt 33b only is rotated counter clockwise so that the person 36 can be conveyed without slippage between the contacting surfaces. A number of apparatuses for conveying incumbent persons which operate on this principle have been developed. These are described, for example, in U.S. Pat. Nos. 3,947,902, 3,967,328, 4,073,016, 4,077,073 and 4,680,818, U.S. patent application Ser. No. 031,668, and Japanese Patent Publication Nos. 47(1972)-34477, 56(1981)-16659, 56(1981)24536 and 56(1981)-34298. As a system Which has actually been marketed there can be mentioned the Full Automatic Stretcher DR-520 sold by Takara Belmont K.K. of Japan.
The incumbent person conveying devices employing these methods are capable of conveying an incumbent person with relatively small driving power but, depending on the use circumstances, entail a problem which arises from the fact that these belt-type conveying apparatuses are ordinarily designed solely for conveying a person lying on his or her back on a hard, inflexible supporting surface and operate by inserting the plate member into a gap between the person and the supporting surface. Thus when there is a difference in level exceeding the thickness of the plate member, a high degree of resistance arises and in some cases conveyance may be altogether impossible. It has been found through actual use that when such an apparatus is used to convey a person lying face up on a spring bed and causing the bed surface to be depressed to a relatively large extent, the person experiences a considerable pressure and friction.